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What is collective immunity and why for some would end the coronavirus pandemic?

2020-04-24T02:52:24.257Z


Collective immunity, also called collective protection, is what happens when the majority of the population is immune to an infectious disease. But it is not so easy to achieve.


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This is how the new coronavirus is detected, explains Jorge Geffner 4:10

(CNN) - The concept of collective immunity is simple. But do you do it? Not that much.

As the coronavirus pandemic spread around the world, doctors, scientists, and government leaders have similarly said that when mass immunity is achieved, the spread of the virus would be less of a threat.

  • READ: Immunity cards, gender confinement and other unusual tactics to fight covid-19 worldwide

Now, collective immunity is achieved when the majority of a given population - between 70% and 90% - become immune to an infectious disease, either because they spread and recovered, or through vaccination. When that happens, the disease is less likely to spread to people who are not immune, because there simply are not enough infectious carriers to affect them.

There are only two ways to get there: a general vaccination - for which in the case of covid-19 there are still many months to go - or widespread infections that lead to immunity.

This graphic from the National Institute of Allergy and Infectious Diseases explains the concept of collective immunity.

Collective immunity from infection is not without risks

Most doctors and experts agree that allowing covid-19 to simply spread to populations could help to achieve collective immunity more quickly. However, that would also saturate hospitals. More people would die, not only from the coronavirus but also from other infections. That is why we are all at home: we try to flatten the curve.

"The advantage of containing the number of cases is that we will not exceed the capacity of hospitals to care for those who are especially ill," explained Dr. H. Cody Meissner, head of pediatric infectious diseases at the University School of Medicine. from Tufts, in conversation with CNN's Michael Smerconish in March.

And then comes the problem that we really don't know how immunity works with this virus.

Several people enjoy the warm spring weather by the water in Hornstull, Stockholm on April 21 during the coronavirus pandemic.

Dr. Maria Van Kerkhove, an infectious disease epidemiologist at the World Health Organization (WHO), said it is not known whether people who have been exposed to the virus become completely immune, and if so, for how long. That is why governments should expect a vaccine, he added.

The WHO "has seen some preliminary results, some preliminary studies, previously published results, in which some people develop an immune response," said Van Kerkhove. Now, he clarified: "We don't know if that really confers immunity, which means that they are fully protected."

A vaccine is the best answer, he insisted. "I mean, we recently had over 130 developers, scientists, and companies come together to say they would be willing to work with us ... to work globally to advance a vaccine. And that is something that we will promote and that the whole world is waiting for, ”he said.

And while young people are much less likely to die from covid-19, they can still get sick enough to require hospitalization.

Young people get, get sick, and spread the coronavirus 3:33

Even if catching covid-19 at some point results in people being immune to future infections, the United States does not have enough cases to come close to crowd immunity.

"The level of people who have been infected, I do not expect to reach the level of what we call collective immunity protection," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in an interview with Jim Scuitto of CNN.

"What it will mean is that it would protect those who have been exposed, but at the community level there would not have been enough infections to really have enough collective immunity," added Fauci.

As a vaccine for the new coronavirus has not yet been produced, some have argued that nations should give up confinement measures altogether and try to achieve collective immunity, by keeping vulnerable people in isolation and allowing others to live. their daily lives and are contagious.

  • READ: The estimated period for a coronavirus vaccine is 18 months. Experts say it is risky

Britain's Prime Minister Boris Johnson seemed to support a similar belief in March, when he was slow to ban large gatherings and close schools.

However, Johnson later issued a national confinement order, effectively closing all nonessential businesses and banning public meetings. He then contracted the virus and spent three nights in the intensive care unit. He was finally released from the hospital.

Boris Johnson was released and thanks the medical staff 1:25

Why does Sweden refuse confinement?

While the vast majority of Europe is under restrictions of social distancing, one country has refused to follow the trend: Sweden

Restaurants, schools and playgrounds in the Scandinavian country remain open. Swedish Foreign Minister Ann Linde has said she does not follow the theory of collective immunity, but is confident that her citizens are responsible, on a voluntary basis, for preventing the spread of the coronavirus.

However, Sweden's state epidemiologist Anders Tegnell claimed that collective immunity could be achieved in the nation's capital Stockholm in a matter of weeks.

"In the main areas of Sweden, around Stockholm, we have reached a standstill (in new cases) and we are already seeing the effect of collective immunity and in a few weeks we will see even more of the effects of that," Tegnell said in a interview with CNBC.

Sweden refuses to order confinement 0:26

The strategy has not come without consequences.

The WHO has warned that it is "imperative" that Sweden take stricter measures to control the spread of the virus.

Compared to other European nations that have not taken strict measures, Sweden's "curve" - ​​the rate of contagion and death caused by the coronavirus - is more pronounced. As of Wednesday, Sweden reported at least 1,937 covid-19-related deaths, compared to 185 deaths in Norway and 149 in Finland, according to data from Johns Hopkins University.

The pressure for antibody tests

It is difficult to know where the United States is currently without widespread screening tests. This is why so many people are pushing for antibody tests.

With a finger prick, tests - aimed at detecting whether you've contracted the coronavirus - can help public health officials determine how much of the population has been infected and - in theory - at least have some immunity to the virus. said Caroline Buckee, an associate professor of epidemiology at Harvard University's TH Chan School of Public Health.

How can antibodies help in a pandemic? 1:05

A city in California has already started testing for antibodies on its residents. New York Governor Andrew Cuomo said his state, the hardest hit in the United States, would begin large-scale antibody testing next week.

"This will be the first real image of what we are dealing with," said Cuomo.

But scientists and doctors are skeptical about the reliability of the dozens of tests that have hit the market because many have not been reviewed by the Food and Drug Administration (FDA).

  • LOOK: What are antibody tests and what do they mean for the coronavirus pandemic?

Also, even passed tests are never 100% accurate.

The FDA also warned that the tests could lead to false negatives, because the antibodies may not be detectable early in the infection.

Tim Lister, Sebastian Shukla, Nina dos Santos, Paula Hancocks, Yoonjung Seo, Julia Hollingsworth, Mallory Simon, Gina Yu, Curt Devine, Drew Griffin, Nelli Black, Scott Bronstein, Kristina Sgueglia, Augie Martin and Sanjay Gupta, all from CNN, contributed to this report.

Communitycovid-19Immunityprevention

Source: cnnespanol

All news articles on 2020-04-24

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